Method for estimating the tread depth of vehicle tyres for vehicles with twin tyres

Abstract

The invention relates to a method for estimating the tread depth of vehicle tires on a vehicle with twin tires, comprising the following method steps: a) driving a twin-tired vehicle along a predetermined driving distance in a driving section, b) determining a plurality of driving parameters (10) of the vehicle during the drive, wherein the plurality of driving parameters (10) includes at least the lateral acceleration, and, for the inner and outer vehicle tires of the twin tires, the following method steps: c) calculating the forces (12) acting on the vehicle tires in the driving section based on the determined driving parameters (10) and determining an abrasion severity index (14) assigned to the driving section from the calculated forces (12), taking into account a plurality of influencing parameters (16) selected from the group consisting of vehicle parameters (16a).environmental parameters (16b) and tire parameters (16c), wherein the influencing parameters (16) include at least information on the tread material and the initial tread depth, taking into account the position of the respective vehicle tire in the twin tire configuration by a position correction factor (18), and d) estimating the final tread depth for the vehicle tire starting from the respective initial tread depth, taking into account the respective wear index (14).

Description

[0001] The invention relates to methods for estimating the tread depth of vehicle tires in a vehicle with dual tires, as well as to a vehicle designed to implement the method. A computer program product for implementing steps of the corresponding method is also disclosed.

[0002] Advancing technological development and increasing digitalization are particularly affecting the field of automotive technology and vehicle tires. There is continued interest in continuously recording operating data from the components used in vehicles, for example, to continuously monitor performance and operational reliability. One important piece of information that can be monitored, for example, in vehicle tires, is the tread depth, as this value regularly correlates well with the durability and condition of the tires and can be used, for example, to determine the optimal time to replace tires.

[0003] There is fundamentally a great interest in being able to estimate and / or calculate the tread depth of tires individually for each tire during operation and as accurately as possible, so that a precise individual value for the tread depth of the tread is available for all tires of a vehicle, preferably without the driver having to determine the tread depth himself.

[0004] Various methods for estimating and / or calculating tread depth are known from the prior art, but they each have different advantages and disadvantages. Related prior art is disclosed, for example, in CN 112976956 A, EP 0972658 B1, US 9340211 B1, US 2021 / 0302272, and DE 102018200358 A1.

[0005] For example, methods are known that allow conclusions to be drawn about the tread depth of the tire's tread by measuring the radial acceleration of a vehicle tire using an acceleration sensor on the tire's inner liner. For example, DE 102015216210 A1 discloses a method that allows the tread depth to be calculated from the radial acceleration using a system of linear equations. EP 2172759 B1 calculates the tread depth from the minimum or maximum of the time differential of the radial acceleration within a defined time interval, in particular within a time interval in which the acceleration sensor traverses the wheel contact patch.A vehicle comprising an axle with at least one twin tire arrangement with an inner vehicle tire and an outer vehicle tire, as well as a method for estimating the tread depth of vehicle tires in a vehicle with twin tires, is known from US2021181064 A1.

[0006] Other methods rely on the correlation of the vehicle speed, determined for example by means of GPS data, with the rotational speed of the vehicle tire, whereby the tread depth of the vehicle tire is derived from the initial tread depth and the change in the dynamic rolling radius, which can be obtained from the correlation of the vehicle speed with the rotational speed of the vehicle tire.

[0007] These processes usually require additional sensors in the vehicle tires or their peripherals. However, these sensors not only increase the manufacturing costs of the vehicle tires, but in many cases, sensors built into the vehicle tires are also susceptible to malfunctions caused by the severe mechanical stresses encountered during driving. For this reason, many vehicle tires in use today do not have additional sensors that would enable the use of such processes.

[0008] Against this background, data-based methods for estimating the tread depth of vehicle tires have been proposed, in which the tread depth of vehicle tires is calculated based on vehicle parameters, in particular the vehicle speed or the acceleration values of the vehicle, as well as a set of different influencing parameters, for example the condition of the vehicle, the type of tires or the prevailing environmental conditions, whereby the number of influencing parameters included in the calculation can vary with the respective application scenario and the desired precision of the calculation.

[0009] Methods for estimating and / or calculating tread depth are particularly interesting for use in commercial vehicle fleet management. Many commercial vehicles, such as trucks, have one or more axles with so-called twin tires, also known as dual tires. This means that the corresponding vehicle axle has a twin tire set consisting of two tires arranged side by side on at least one side, but more often on both sides, which are mounted together on a corresponding axle mount. Such a twin tire setup usually serves to better distribute the axle weight and is often advantageous for commercial vehicles.

[0010] However, the inventors have found that the adjacent arrangement of vehicle tires in a twin tire set makes it difficult to correctly estimate the tread depth using the inherently advantageous data-based methods, as these methods essentially do not differentiate between the vehicle tires in a twin tire set. However, the inventors have recognized that this can lead to inadequate results in estimating the tread depth and that, in the worst case, the use of these methods in the case of twin tires can result in the actual condition of one of the vehicle tires in the twin tire set being significantly worse than would have been assumed based on the data-based method for estimating the tread depth.

[0011] The primary object of the present invention was to eliminate or at least mitigate the disadvantages of the prior art described above.

[0012] In particular, it was an object of the present invention to provide a method for estimating the tread depth of vehicle tires, with which the tread depth of vehicle tires can be estimated reliably and efficiently, wherein sensors arranged in the vehicle tire should desirably be dispensed with, so that the method can be carried out with all commercially available vehicle tires.

[0013] It was an object of the present invention that the method to be specified should enable a particularly precise estimation of the tread depth of vehicle tires in twin packages of twin-tired vehicles.

[0014] It was a further object of the present invention that the method to be specified should enable a reliable estimation of the tread depth of vehicle tires, in particular during driving, and thus enable the most time- and cost-efficient fleet management possible for the operators of commercial vehicle fleets.

[0015] Furthermore, it was an object of the present invention to provide a vehicle which is equipped to carry out the method to be specified.

[0016] It was a secondary object of the present invention to provide a computer program product for carrying out selected steps of the method to be specified.

[0017] The inventors of the present invention have now recognized that the objects described above can surprisingly be achieved if, in a specific data-based method for estimating the tread depth of vehicle tires with twin tires, the lateral acceleration is always included in the calculation as a driving parameter, if at least information about the tread material of the vehicle tire and about the initial tread depth is taken into account as influencing parameters, provided that the calculation for the vehicle tires in the twin tires is carried out using a position correction factor, as defined in the claims.

[0018] The above-mentioned objects are thus achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following statements.

[0019] Such embodiments, which are designated as preferred below, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments designated as particularly preferred below are thus very particularly preferred. Likewise preferred are embodiments in which a feature of an embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent. Features of preferred vehicles and computer program products result from the features of preferred methods.

[0020] The invention particularly relates to a method for estimating the tread depth of vehicle tires in a vehicle with twin tires, comprising the method steps: a) Driving a vehicle along a predetermined driving distance in a driving section, wherein the vehicle comprises at least one axle with at least one dual tire arrangement with an inner vehicle tire and an outer vehicle tire, b) Determining a plurality of driving parameters of the vehicle while driving in the driving section, wherein the plurality of driving parameters includes at least the lateral acceleration, and the method steps for each of the inner vehicle tire and the outer vehicle tire of the dual tire arrangement: c) Calculating the forces acting on the vehicle tires in the driving section based on the determined driving parameters and determining an abrasion severity number assigned to the driving section from the calculated forces, taking into account a plurality of influencing parameters, wherein the influencing parameters are selected from the group consisting of vehicle parameters, environmental parameters, and tire parameters,wherein the influencing parameters comprise at least information about the tread material of the vehicle tire and about the initial tread depth at the beginning of the driving section, wherein the position of the respective vehicle tire in the twin tire arrangement is taken into account by a position correction factor, and d) estimating the final tread depth at the end of the driving section for the vehicle tire based on the respective initial tread depth at the beginning of the driving section, taking into account the respective abrasion severity number.

[0021] The method according to the invention is used to estimate the tread depth of vehicle tires in a vehicle with dual tires and is therefore particularly suitable for commercial vehicles. Accordingly, a method according to the invention is also preferred, wherein the vehicle is a commercial vehicle, preferably a truck or a bus, preferably a truck.

[0022] The advantages of the method according to the invention become apparent with increasing numbers of axles with twin tires or the number of twin sets, since the methods known from the prior art are often particularly error-prone for these vehicles. Accordingly, a method according to the invention is preferred, wherein the vehicle comprises two or more axles with at least one twin tire.

[0023] In the context of the present invention, in a twin tire arrangement, the vehicle tire located on the vehicle side or pointing in the direction of the axle center is considered to be the inner vehicle tire.

[0024] As already explained above, axles with dual tires usually have a twin tire set on both sides. In practice, a method according to the invention is relevant for essentially all embodiments, wherein the vehicle comprises at least one axle with dual tires on both sides, each with an inner vehicle tire and an outer vehicle tire. The method is preferably carried out for all vehicle tires of the dual tire set.

[0025] Those skilled in the art will understand that the method according to the invention is directed at the particularly demanding step of estimating the tread depth of vehicle tires in dual tire configurations, but that this does not preclude the possibility of additional vehicle tires on normal axles also being evaluated for tread depth. In this case, a method according to the invention is preferred, wherein the method is additionally carried out for vehicle tires that are not part of a dual tire configuration, wherein no position correction factor is taken into account when determining the wear severity index.

[0026] The advantage of the method according to the invention is that it does not require sensors in the vehicle tires to estimate the tread depth, and commercially available vehicle tires can be used. With regard to cost efficiency and maintenance requirements, it is also advantageous to use such conventional vehicle tires. Therefore, a method according to the invention is preferred, wherein the inner vehicle tire and the outer vehicle tire, preferably all vehicle tires of the vehicle, do not include any speed or acceleration sensors, and preferably no electronic sensors at all.

[0027] The final tread depth of the vehicle tires obtained at the end of the method according to the invention can advantageously be made available to the driver directly as information, for example, directly as the remaining tread depth or as an indication of an upcoming maintenance and / or tire replacement date. Of particularly high practical relevance and preferred for essentially all embodiments, a method according to the invention additionally comprises the method step: e) outputting information about the estimated final tread depth of the inner vehicle tire and the outer vehicle tire at the end of the driving section via an output unit, preferably via an electronic display device.

[0028] Those skilled in the art will understand that steps c) and d) of the method according to the invention are expediently carried out by an electronic data processing device. In this respect, the inventors primarily propose two different, but possibly combined, approaches for implementing the method according to the invention in a vehicle.

[0029] Firstly, an electronic data processing device can be integrated directly into the vehicle. This advantageously results in a particularly self-sufficient vehicle system in which the method according to the invention can be carried out even if there is no wireless communication connection to the vehicle. Furthermore, corresponding embodiments are often particularly robust and cost-effective to purchase. Thus, firstly, a method according to the invention is preferred, wherein the vehicle comprises an electronic data processing device configured to carry out method steps c) and d) for the inner vehicle tire and the outer vehicle tire of the dual tire arrangement.

[0030] Furthermore, the inventors propose that the electronic data processing device can also be provided as a central unit, for example, as a server of a fleet management system, instead of a decentralized arrangement in the vehicle. This advantageously reduces the computing capacity required in the vehicle. Furthermore, regular maintenance through software updates is easier and, for example, advantageous integration into the rest of the fleet management system can be achieved. Particularly in the embodiments disclosed below, which rely on the use of machine learning, the higher data density that can be achieved in a system comprising several centrally controlled end units can have a beneficial effect on the quality of the estimation, since the modules used can be trained particularly efficiently.Additionally or alternatively, a method according to the invention is thus preferred, wherein the vehicle comprises a device for wireless data transmission, wherein method step b) comprises transmitting the determined driving parameters to an electronic data processing device in a wireless method for data transmission.

[0031] The process steps of the method according to the invention are explained in more detail below.

[0032] In method step a), the vehicle is first driven. Those skilled in the art will understand that this involves driving using the vehicle's tires, which can be self-propelled, for example, in the case of a bus, or by being pulled by a tractor unit, for example, a truck trailer. Moving a vehicle without the use of tires, for example, on a freight train or transport trailer, does not constitute driving the vehicle within the meaning of the present invention. In other words, in practice, this particularly involves a method according to the invention, wherein the vehicle is driven in road traffic.

[0033] The driving takes place over a predetermined driving distance, whereby the time or distance between the beginning and the end of the predetermined driving distance is referred to as the driving section. In the context of the present invention, the driving section is the temporal or spatial interval in which an estimate of the tread depth is made. Those skilled in the art understand that the length of the driving section correlates with the data quality that can be fed into the method according to the invention. Even if it would be possible in principle to create very short driving distances such as 100 m, the inventors propose that the predetermined driving distance should not be chosen too short to enable a particularly reliable determination of the driving parameters.As a result, any measurement errors and uncertainties in determining the driving parameters are balanced out over time, and special events during the journey, such as heavy emergency braking, have a proportionally less significant impact. Accordingly, a method according to the invention is preferred, wherein the predetermined driving distance is in the range of 0.5 to 20 km, preferably in the range of 1 to 10 km.

[0034] In the method according to the invention, it is necessary to determine a plurality of driving parameters of the vehicle. At least the lateral acceleration must be determined. However, since the invention involves a plurality of driving parameters, at least one further driving parameter, for example the longitudinal acceleration, must be determined in addition to the lateral acceleration. The more driving parameters available, the more precisely the calculation of the acting forces and the calculation of the abrasion severity number can be carried out in most cases. A method according to the invention is preferred, wherein the plurality of driving parameters, in addition to the lateral acceleration, comprise at least the longitudinal acceleration and / or the Z-acceleration and / or the speed, preferably the longitudinal acceleration and the Z-acceleration and / or the speed, particularly preferably the longitudinal acceleration and the Z-acceleration and the speed.

[0035] With regard to the quality of the data obtained and the immediacy of the determination in the driving section, the inventors believe it is particularly advantageous if the driving parameters are determined at least partially, preferably essentially completely, via vehicle-internal sensors, which are often available anyway in modern vehicles, so that already available sensors can be incorporated in a synergistic manner into the method according to the invention for estimating the tread depth.Accordingly, a method according to the invention is preferred, wherein the vehicle comprises one or more driving parameter sensors for determining a plurality of driving parameters of the vehicle during travel, wherein the plurality of driving parameters comprises at least the lateral acceleration, and / or wherein the determination of the plurality of driving parameters of the vehicle is carried out by one or more driving parameter sensors of the vehicle, wherein the driving parameter sensors are preferably selected from the group consisting of speed sensors and acceleration sensors.

[0036] The inventors have recognized that time-dependent position data of the vehicle, such as those accessible via GPS, can also be efficiently utilized in the method according to the invention. In a particularly preferred embodiment, this data can be used to verify and / or correct the driving parameters determined by vehicle sensors, for example by comparing a speed measured in the vehicle with the speed determined from time-dependent position data of the vehicle, for example to compensate for errors in the vehicle-side sensors. Alternatively, in less preferred embodiments of the method, all driving parameters required for the method can also be determined from the time-dependent position data, although in the inventors' opinion, this procedure is more suitable for rougher estimates given the current state of technology.In summary, a method according to the invention is preferred, wherein the determination of the plurality of driving parameters of the vehicle is carried out by evaluating time-dependent position data, preferably GPS data, or is supported thereby, preferably supported thereby.

[0037] Those skilled in the art will understand that the vehicle's driving parameters are determined during the driving segment, and that the word "during" here refers to a continuous determination at multiple points in time during the driving segment. According to the expert's understanding, the higher the temporal resolution in the data acquisition, the more precise the calculation of the time-dependent forces becomes. As is common practice in sensor and measurement technology, the vehicle's driving parameters are determined at a specific frequency that indicates how often the respective driving parameter is determined per second. Very high acquisition frequencies enable a particularly advantageous temporal resolution of the driving parameters, but also generate more storage requirements on the memory unit of the electronic data processing device, require more bandwidth for transmission, and can increase energy consumption.In practice, it is therefore often expedient to keep the determination frequencies relatively low. However, the inventors propose lower limits for the determination frequencies that allow for an advantageous and precise estimation in every case. In this respect, a method according to the invention is preferred, wherein the determination of the majority of the vehicle's driving parameters is carried out for each driving parameter using a determination frequency assigned to the driving parameter, wherein the determination frequency is preferably 4 Hz or more, particularly preferably 6 Hz or more, particularly preferably 12 Hz or more.

[0038] Following the method steps a) and b) of the method according to the invention, the method steps c) and d) are now carried out for the two vehicle tires in the twin tire arrangement or potentially for all vehicle tires in all twin tire arrangements of the vehicle.

[0039] In process step c), the time-dependent forces acting on the respective vehicle tire during the driving section are first calculated from the determined driving parameters, specific to each vehicle tire. In relation to the coordinate system commonly used in the vehicle tire industry, this is done, for example, with reference to the force components Fx(t), Fy(t), and Fz(t), i.e., the time-dependent forces in the longitudinal direction, transverse direction, and radial Z-direction. The calculation of these forces from the driving parameters, in particular the determined accelerations, is possible for the expert based on their specialist knowledge, adapting the methodology to the respective requirements, in particular to the precision of the determination.In this case, for example, in addition to comparatively simple calculation algorithms, reference-based methods can also be used which rely on comparison with previously recorded reference measurements or reference simulations, whereby approaches which rely on machine learning are also possible. In the majority of cases, however, the person skilled in the art will resort to simulation methods such as those commonly used in the industry to calculate forces. For this purpose, the person skilled in the art has access to a variety of commercially available software solutions, which the person skilled in the art can adapt to their requirements if necessary. Accordingly, a method according to the invention is also preferred, wherein the forces acting on the vehicle tires during the driving section are calculated on the basis of the determined driving parameters by an electronic data processing device using a simulation program.

[0040] From the forces acting on the respective vehicle tires during the driving section, a measure of the load on the vehicle tires during the driving section can be determined, which influences the wear. This key figure indicates how strong - i.e. sharp - the mechanical load on the vehicle tire was during the driving section and how high the expected wear is. Against this background, the term "abrasion severity number" is expediently used within the context of the present invention. In accordance with the understanding of those skilled in the art, however, the exact name of this parameter is just as irrelevant in the practical implementation of the method according to the invention as the programming implementation of the parameter, for example in the computer program product. For example, it is conceivable that the abrasion severity number has different dimensions depending on the calculation method or is even generated as a set of several abrasion severity numbers.In accordance with the expert understanding, the only relevant factor for the abrasion severity number is that the abrasion severity number is a measure of the abrasion-relevant mechanical load of the respective vehicle tire, determined from the calculated time-dependent forces, which it experienced during the driving section.

[0041] According to the invention, the forces acting on the vehicle tires during the driving section are calculated, as well as the abrasion severity index assigned to the driving section, from the calculated forces, each taking into account a plurality of influencing parameters. These influencing parameters, which are vehicle parameters, environmental parameters, and tire parameters, thus influence the calculation of the forces and / or the calculation of the abrasion severity index assigned to the driving section. The inventors have recognized that, for the method according to the invention to function, these influencing parameters must in any case include information about the tread material of the vehicle tire and about the initial tread depth at the beginning of the driving section. These influencing parameters are each tire parameters, i.e., properties of the corresponding vehicle tires.

[0042] In this case, according to the inventors' assessment, the vehicle parameters are expediently considered predominantly, or in some cases even exclusively, when calculating the forces acting on the vehicle tires during the driving section. The vehicle parameters, e.g., information on the chassis characteristics, can be included as input in the simulation of the forces. In contrast, the environmental parameters and tire parameters are more likely to be considered when determining the wear severity index, for example, because the effect of an abrasion severity index is determined in light of the prevailing ambient temperatures and the tire type, e.g., the winter tire version.

[0043] In method step c), the inventors also believe that a larger number of influencing parameters will, in principle, increase the quality of the obtained estimate. However, in practice, it will be necessary to weigh up for each influencing parameter whether its consideration justifies the additional computational effort. A method according to the invention is preferred, wherein the forces acting on the vehicle tire during the driving section are calculated and the abrasion severity index assigned to the driving section is determined from the calculated forces, taking into account three or more, preferably four or more, particularly preferably six or more, and most particularly preferably eight or more, influencing parameters.

[0044] In the inventors' opinion, comprehensive consideration of vehicle parameters is expedient, particularly in order to obtain the most accurate picture possible of the forces and their temporal development, especially when calculating the forces. Accordingly, a method according to the invention is also preferred, wherein the calculation of the forces acting on the vehicle tires during the driving section and / or the determination of the wear severity index assigned to the driving section, preferably the calculation of the forces acting on the vehicle tires during the driving section, takes place taking into account one or more, preferably two or more, particularly preferably three or more, vehicle parameters, wherein the vehicle parameters are particularly preferably taken into account within the framework of a force simulation.

[0045] When taking vehicle parameters into account, a method according to the invention is preferred, wherein the vehicle parameters are selected from the group consisting of information on the wheelbase, track width, vehicle weight, wheel load, tire camber, slip angle, drive type, and drive concept. When taking vehicle parameters into account, a method according to the invention is preferred, additionally or alternatively, wherein the vehicle parameters are provided depending on the vehicle type and / or vehicle configuration, preferably on the memory unit of an electronic data processing device.

[0046] According to the inventors, taking environmental parameters into account is particularly advantageous when the environmental conditions expected in an application scenario differ significantly from those for which the method according to the invention was optimized, for example because reference measurements were carried out in regions with a temperate climate, but the method according to the invention is to be used in a tropical or arctic region. Furthermore, taking environmental parameters into account is expedient when larger variations in the environmental conditions are to be expected in the application scenario, for example as a result of pronounced seasonal changes. According to the inventors, this can be taken into account particularly easily in many cases, for example as scaling factors for the resulting abrasion, which can be obtained, for example, from reference measurements under different environmental conditions.A method according to the invention is therefore preferred, wherein the calculation of the forces acting on the vehicle tires in the driving section and / or the determination of the abrasion severity number assigned to the driving section, preferably the determination of the abrasion severity number assigned to the driving section, takes place taking into account one or more, preferably two or more, particularly preferably three or more, environmental parameters.

[0047] A method according to the invention is preferred, wherein the environmental parameters are selected from the group consisting of information on the ambient temperature, road surface humidity, weather and road surface roughness.

[0048] To obtain the environmental parameters, the inventors propose that they can be detected particularly efficiently and directly by sensors that are already provided in the vehicle. In this case, a method according to the invention is preferred, wherein the environmental parameters are obtained at least partially by one or more environmental sensors of the vehicle.

[0049] Additionally or alternatively, environmental parameters can also be obtained at least partially indirectly by relying on position data and associated information, so that internal sensors can be dispensed with, particularly in older vehicles. From the vehicle's location, for example, information about the road surface, such as whether it is a motorway, a country road, or a track, or about the local weather forecast and ambient temperatures, can be obtained. Thus, additionally or alternatively, a method according to the invention is preferred, wherein the environmental parameters are obtained at least partially by comparing time-dependent position data, preferably GPS data, with spatially resolved environmental data.In this respect, a method according to the invention is preferred, wherein the spatially resolved environmental data are selected from the group of weather data and road maps with indication of the road type and / or road surface.

[0050] According to the invention, at least two tire parameters must be taken into account, namely the information about the tread material of the vehicle tire and the initial tread depth of the vehicle tire at the beginning of the driving section.

[0051] The inventors believe that the first of these tire parameters is important because the material properties of the tread are largely responsible for the expected wear. The tread material can be taken into account, in particular, by comparing it with reference measurements on similar or identical tread materials, for example, when a reference abrasion behavior is determined in reference experiments for one or more characteristic materials under suitable abrasion severity values, possibly under specific ambient or road temperatures. Accordingly, a method according to the invention is also preferred, wherein the information about the tread material of the vehicle tire includes information about the physicochemical properties of the tread material, preferably the glass transition temperature of the polymer used in the tread and / or the abrasion resistance of the tread, preferably the abrasion resistance of the tread.

[0052] The second of these tire parameters is important because the respective wear rate also depends on the current tread depth. This is often attributed to the varying stiffness of the individual tread blocks depending on the tread depth and the resulting different "snap-out behavior" when leaving the ground contact patch. Taking this tire parameter into account is advantageously usually not associated with additional effort, since the initial tread depth at the beginning of the driving section will in most cases be used as the starting value for calculating the final tread depth anyway, since in practice, providing information on absolute tread depths is often preferred over merely relative changes.

[0053] To obtain the required information about the initial tread depth of the vehicle tire at the beginning of the driving section, the inventors envisage two options in particular. Determining the initial tread depth at the beginning of the driving section by actual measurement, for example, manually by the driver, regularly yields particularly accurate results in estimating the subsequent final tread depth. However, since this approach is only practical for the first driving section of each journey, this method is less preferred. A method according to the invention is preferred, particularly for certain applications with high demands on the precision of the estimation, in which the initial tread depth is measured at the beginning of the driving section before the driving section.

[0054] Particularly with regard to the workload of the vehicle driver, it is preferred, however, if the result of a first estimate in the method according to the invention is subsequently used as a starting point in the subsequent driving section. This can advantageously be carried out so far that the initial input of the initial tread depth occurs only once, e.g., when changing tires, and the method subsequently continues to work with values that it has previously obtained as a result of an estimate. Accordingly, a method according to the invention is particularly preferred, wherein the method is carried out for two or more driving sections, wherein the final tread depth estimated for the previous driving section at the end of the previous driving section is used for the initial tread depth at the beginning of the second or a further driving section.

[0055] In addition to the tire parameters that must be considered in any case according to the invention, it may be expedient to consider additional tire parameters to further increase precision. A method according to the invention is preferred, wherein the calculation of the forces acting on the vehicle tire during the driving section and / or the determination of the wear severity index assigned to the driving section, preferably the determination of the wear severity index assigned to the driving section, takes place taking into account three or more, preferably four or more, particularly preferably five or more, tire parameters.

[0056] A method according to the invention is preferred, wherein the tire parameters are selected from the group consisting of information on tire size, tire pressure, profile geometry, and tire stiffness. Additionally or alternatively, a method according to the invention is preferred, wherein the tire parameters are provided depending on the tire type and / or the tire configuration of the vehicle tires, preferably on the memory unit of an electronic data processing device.

[0057] In practice, the inventors believe that the tire parameters of two vehicle tires in a dual tire configuration will often be largely identical, for example, with regard to the tire type and / or tire profile. However, the inventors have recognized that among the various tire parameters, one parameter varies more frequently between the vehicle tires in a dual tire configuration: tire pressure. Particularly in strong sunlight, tire pressure can vary between the inner and outer tires, even if the tires were originally filled to the same pressure. However, a vehicle tire with higher air pressure will bear a greater load than a vehicle tire with lower air pressure, resulting in greater wear.For a particularly extensive consideration of the special features of a twin tire system when estimating the remaining tread depth, a method according to the invention is particularly preferred, wherein the calculation of the forces acting on the vehicle tire in the driving section and / or the determination of the abrasion severity number assigned to the driving section, preferably the determination of the abrasion severity number assigned to the driving section, takes place taking into account one or more tire parameters, wherein at least one of the tire parameters, preferably the tire pressure, is different for the inner vehicle tire and the outer vehicle tire.

[0058] Regardless of any pressure differences between the inner and outer vehicle tires of a dual tire arrangement, the inventors recognized that a position correction factor must be used to account for the fact that the vehicle tires of the dual tire arrangement on the outside of the curve experience greater forces when cornering than the vehicle tires on the inside. As a result, the vehicle tires of the dual tire arrangement on the outside of the curve experience greater wear. In other words, this is a method according to the invention, wherein the position correction factor is preferably applied as a correction factor to the forces experienced as a result of lateral acceleration, in particular to the force Fy(t).

[0059] In the simplest embodiment, the position correction factor can be largely estimated by a person skilled in the art, for example, to account for the proportion of right-hand and left-hand bends in the traveled section for the vehicle tires of the twin tire set. In this respect, a method according to the invention is preferred, wherein the position correction factor during cornering for each vehicle tire of the twin tire set is in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1, particularly preferably in the range of 0.95 to 1.05, with values above 1 applying to vehicle tires on the inside of the curve, and vice versa.

[0060] In In process step d), the final tread depth at the end of the driving section is now estimated based on the initial tread depth at the beginning of the driving section, taking into account the respective abrasion severity number.

[0061] A variety of options are available to the expert for this purpose. The estimation can be performed, for example, by comparing it with data recorded in reference measurements for vehicle tires with corresponding wear severity numbers. This can yield, for example, a relative change in tread depth and / or a reduction in tread depth by an absolute value and / or a resulting final tread depth. Influencing parameters, such as temperature, can be taken into account again if necessary.

[0062] One example is a method according to the invention, wherein when estimating the final tread depth at the end of the driving section, an abrasion value is subtracted from the initial tread depth, wherein the abrasion value is obtained by multiplying the driving distance by the determined abrasion severity number and by the quotient of a reference abrasion value and an associated reference abrasion severity number, wherein the reference abrasion value and the associated reference abrasion severity number are obtained from one or more reference measurements of the abrasion behavior of reference vehicle tires. Another example is a method according to the invention, wherein the abrasion value is obtained as a temperature-corrected abrasion value by additional multiplication by a temperature factor, for example the quotient of the ambient temperature (in Kelvin) when determining the abrasion severity numbers and the ambient temperature when determining the reference abrasion severity number.

[0063] In this respect, a method according to the invention is preferred, wherein the reference vehicle tires substantially correspond to the tire parameters of the vehicle tires with respect to at least one, preferably with respect to the majority, particularly preferably with respect to all, tire parameters, preferably at least with respect to the tread material. In this respect, additionally or alternatively, a method according to the invention is also preferred, wherein the reference abrasion severity number is calculated using a reference method that substantially corresponds to the vehicle parameters of the method with respect to at least one, preferably with respect to the majority, particularly preferably with respect to all, vehicle parameters.

[0064] In addition, the final tread depth can be estimated using machine learning, whereby the person skilled in the art can, for example, train corresponding commercially available programs within the framework of supervised learning with known abrasion severity numbers and associated abrasion values as well as, if necessary, other influencing parameters from reference experiments. In this case, a method according to the invention is preferred, wherein the final tread depth is estimated at the end of the driving section using a machine learning-based estimation module stored in the memory unit of an electronic data processing device, wherein the electronic data processing device is configured to determine the driving distance in the driving section, the determined abrasion severity number of the vehicle tire in the driving section, and the initial tread depth at the beginning of the driving section, as well as optionally other influencing parameters,as input to the estimation module and to estimate the final tread depth based on the input, wherein the estimation module is trained to estimate the final tread depth at the end of the driving section from the driving distance in the driving section, the determined wear severity index of the vehicle tire in the driving section and the initial tread depth at the beginning of the driving section and optionally further influencing parameters, wherein the training is carried out with a set of training data comprising a plurality of known tread depths obtained from known initial tread depths as a result of known wear severity indexes after known driving distances.

[0065] A method according to the invention is preferred, wherein the estimation module is based on a machine learning algorithm selected from the group consisting of supervised learning, preferably selected from the group consisting of logistic regression, support vector machines, K-nearest neighbors methods, decision tree methods and artificial neural networks, preferably artificial neural networks, and / or wherein the estimation module is obtained by applying a machine learning algorithm to the set of training data, wherein the algorithm is selected from the group consisting of supervised learning, preferably selected from the group consisting of logistic regression, support vector machines, K-nearest neighbors methods, decision tree methods and artificial neural networks, preferably artificial neural networks.

[0066] Additionally or alternatively, a method according to the invention is preferred, wherein the training is carried out with a set of training data which correspond to the influencing parameters of the method with regard to at least one, preferably with regard to the majority, particularly preferably with regard to all, influencing parameters.

[0067] The invention also relates to a vehicle which is specifically designed for carrying out the method according to the invention, comprising: i) at least one axle with at least one pair of twin tires with an inner vehicle tire and an outer vehicle tire, ii) one or more driving parameter sensors for determining a plurality of driving parameters of the vehicle while traveling along a predetermined driving distance in a driving section, wherein the plurality of driving parameters includes at least the lateral acceleration, and iii) an electronic data processing device, wherein the data processing device is configured to carry out the following calculation steps for the inner vehicle tire and the outer vehicle tire of the twin tires: cc) calculating the forces acting on the vehicle tires in the driving section based on the determined driving parameters and determining an abrasion severity number assigned to the driving section from the calculated forces, taking into account a plurality of influencing parameters,wherein the influencing parameters are selected from the group consisting of vehicle parameters, environmental parameters and tire parameters, wherein the influencing parameters comprise at least information about the tread material of the vehicle tire and about the initial tread depth at the beginning of the driving section, wherein the position of the respective vehicle tire in the twin tires is taken into account by a position correction factor, and dd) estimating the final tread depth at the end of the driving section for the vehicle tire based on the respective initial tread depth at the beginning of the driving section, taking into account the respective abrasion severity number.

[0068] Finally, a computer program product is also disclosed, comprising instructions which, when the program is executed by an electronic data processing device, preferably an electronic data processing device of a vehicle according to the invention, cause the vehicle to carry out the method steps c) and d) of the method according to the invention.

[0069] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying figures. In the figures: Fig. 1 shows a schematic flow diagram of the method according to the invention in a preferred embodiment; and Fig. 2 shows a schematic flow diagram for an exemplary method step c) in a preferred embodiment.

[0070] Fig. 1 shows a simplified flow chart of the method according to the invention in a preferred embodiment, as it can be carried out, for example, in a vehicle according to the invention with twin tires, for example a truck with two twin-tired axles, in order to estimate the tread depth of the vehicle tires in the twin package.

[0071] In method step a) 100, the vehicle is driven along a predetermined driving distance of, for example, 5 km in a driving section, whereby this driving section can form part of a larger route, whereby it is also possible for the driving section to be interrupted by breaks or downtimes.

[0072] In method step b) 200, the lateral acceleration and other driving parameters 10 are determined. In the preferred method of Fig. 1 In addition to lateral acceleration, the driving parameters 10 also include longitudinal acceleration and Z-acceleration. In the exemplary method, these driving parameters 10 are determined and recorded by the vehicle's integrated driving parameter sensors at a detection frequency of approximately 10 Hz. The determination of the vehicle speed is also supported by the evaluation of time-dependent GPS data to verify the accuracy of the driving parameters 10.

[0073] In the preferred procedure of Fig. 1 the vehicle comprises an electronic data processing device integrated in the vehicle, which not only controls the determination of driving parameters 10, but is also designed to carry out the method steps c) 300 and d) 400 for the inner vehicle tire and the outer vehicle tire of all twin tires.

[0074] In process step c) 300, the forces 12 acting on the respective tires are calculated from the determined driving parameters 10 and from this, wear severity values for the vehicle tires in the driving section are determined. This process step is described in Fig. 2 further visualized in a schematic flow chart.

[0075] In the preferred procedure of the Fig. 2 The determined driving parameters 10 are first processed in the form of raw data in a first sub-step 302, wherein, for example, filters or smoothing algorithms are applied to the data or identified artifacts are removed in order to obtain a processed data set of driving parameters 10. From this data set of driving parameters 10, the forces 12 acting on the respective vehicle tires are calculated in the subsequent sub-step 304, which in the preferred method of the Fig. 2 by simulating the acting forces 12 with simulation software, whereby a variety of vehicle parameters 16a are taken into account as influencing parameters 16 in the simulation to optimize the simulation result, namely the wheelbase, the track width, the vehicle weight and the resulting wheel load, the tire camber, the slip angle and information on the drive type or drive concept. The resulting forces 12 are in the example shown the Fig. 2 for each vehicle tire as force components along the three spatial directions Fx(t), Fy(t) and Fz(t).

[0076] From the calculated forces 12, in sub-step 306 in the example shown, the Fig. 2 In an intermediate step, the respective friction energies are first calculated, taking into account the further influencing parameters 16. In addition to the information about the tread material of the vehicle tire and the initial tread depth at the beginning of the driving section, in sub-step 306, further tire parameters 16c are taken into account, namely information about the tire size, the profile geometry and the tire stiffness. In this case, the preferred method of Fig. 2 In particular, a pressure difference between the inner and outer tyres of the twin tyres is taken into account, which is determined by pressure sensors in the tyres during the journey in the driving section.

[0077] In addition, environmental parameters 16b are also taken into account in sub-step 306 in the form of scaling factors. Information on the ambient temperature and road surface humidity is provided by the vehicle's own sensors. In contrast, information on road surface roughness is derived from time-dependent GPS data, which is correlated with a road map in which typical average road surface roughnesses for different roads or road types (e.g., motorway or country road) are noted.

[0078] In sub-step 308, an abrasion severity number 14 is determined from the results obtained in the form of a single value, for example as an integral of the force action weighted in light of the respective influencing factors over time in the driving section.

[0079] The dashed arrows indicate Fig. 2 It is indicated that the position correction factor 18 is used in one or more of the sub-steps 304, 306, or 308 to account for the different loading of the vehicle tires in twin sets. This takes into account the fact that the vehicle tires on the outside of the curve of the twin tire configuration experience stronger forces 12 when cornering than the vehicle tires on the inside. In the case of an uneven distribution of left and right bends in the driving section, or a generally different absolute load in the different curve directions, as could result, for example, from the fact that the driver generally takes left bends faster, the position correction factor 18 results.This can, for example, be applied to the force component Fy(t) and result, for example, in one of the vehicle tires in the twin package being loaded 5% more and the other 5% less when calculating forces 12 compared to if the tires were treated the same.

[0080] In process step d) 400, in the preferred process, the Fig. 1 The final tread depth at the end of the driving section for the vehicle tyre is estimated based on the respective initial tread depth at the beginning of the driving section and taking into account the respective abrasion severity number 14, whereby in the example shown this is the Fig. 1 by comparing the determined wear severity index 14, weighted to the driving distance, with relative tread depth changes obtained for vehicle tires of the same type with inherently similar influencing parameters 16 as a result of known reference wear severity indexes, whereby the absolute final tread depth can be obtained, for example, from the initial tread depth and the relative change. The dashed arrow in Fig. 1 indicates that the final profile depth estimated in this way at the end of a first driving section can be used in a subsequent method according to the invention as the initial profile depth at the beginning of a subsequent, second driving section in order to avoid an intermediate measurement of the profile depth.

[0081] Finally, in Fig. 1also the method step e) 500 is visualized, in which the driver is provided with information about the estimated final tread depth of the inner and outer vehicle tires at the end of the driving section just completed via a display. List of reference symbols

[0082] 10Driving parameters 12Forces 14Abrasion severity number 16Influencing parameters 16aVehicle parameters 16bEnvironmental parameters 16cTire parameters 18Position correction factor

Claims

1. Method for estimating the profile depth of vehicle tyres on a vehicle with twin tyres, characterized by the method steps of: a) driving a vehicle over a predetermined driving distance in a driving section, the vehicle comprising at least one axle with at least one set of twin tyres comprising an inner vehicle tyre and an outer vehicle tyre, b) determining a plurality of driving parameters (10) of the vehicle during the journey in the driving section, the plurality of driving parameters (10) comprising at least the lateral acceleration, as well as the following method steps in each case for the inner vehicle tyre and the outer vehicle tyre of the set of twin tyres: c) calculating, on the basis of the determined driving parameters (10), the forces (12) acting on the vehicle tyre in the driving section and determining an abrasion index (14), assigned to the driving section and determined according to the method disclosed on page 28, line 10 to page 30, line 14 of the original description, from the calculated forces (12) while taking a plurality of influencing parameters (16) into account, the influencing parameters (16) being selected from the group consisting of vehicle parameters (16a), environmental parameters (16b) and tyre parameters (16c), the influencing parameters (16) comprising at least information concerning the tread material of the vehicle tyre and concerning the initial profile depth at the beginning of the driving section, with the position of the respective vehicle tyre in the set of twin tyres being taken into account by a position correction factor (18), and d) estimating the final profile depth at the end of the driving section for the vehicle tyre on the basis of the respective initial profile depth at the beginning of the driving section while taking the respective abrasion index (14) into account.

2. Method according to Claim 1, wherein the predetermined driving distance is in the range of 0.5 to 20 km.

3. Method according to either of Claims 1 and 2, wherein the determination of the plurality of driving parameters (10) of the vehicle is carried out for each driving parameter (10) with a determination frequency assigned to the driving parameter (10), wherein the determination frequency is 4 Hz or more.

4. Method according to one of Claims 1 to 3, wherein the determination of the plurality of driving parameters (10) of the vehicle is carried out by evaluating time-dependent position data, preferably GPS data, or is assisted thereby.

5. Method according to one of Claims 1 to 4, wherein the calculation of the forces (12) acting on the vehicle tyre in the driving section and / or the determination of the abrasion index (14) assigned to the driving section is / are carried out while taking one or more vehicle parameters (16a) into account, the vehicle parameters (16a) being selected from the group consisting of information on the wheelbase, the lane width, the vehicle weight, the wheel load, the tyre camber, the skew, the drive type and the drive concept.

6. Method according to one of Claims 1 to 5, wherein the calculation of the forces (12) acting on the vehicle tyre in the driving section and / or the determination of the abrasion index (14) assigned to the driving section is / are carried out while taking one or more environmental parameters (16b) into account, the environmental parameters (16b) being selected from the group consisting of information on the ambient temperature, the road moisture, the weather and the road roughness.

7. Method according to one of Claims 1 to 6, wherein the calculation of the forces (12) acting on the vehicle tyre in the driving section and / or the determination of the abrasion index (14) assigned to the driving section is / are carried out while taking three or more tyre parameters (16c) into account, the tyre parameters (16c) being selected from the group consisting of information on the tyre size, the tyre pressure, the profile geometry and the tyre stiffness.

8. Method according to Claim 7, wherein at least one of the tyre parameters (16c), preferably the tyre pressure, is different for the inner vehicle tyre and the outer vehicle tyre.

9. Method according to one of Claims 1 to 8, wherein the position correction factor (18) is applied as a correction factor to the forces (12) experienced as a result of lateral acceleration.

10. Method according to one of Claims 1 to 9, wherein the initial profile depth at the beginning of the driving section is measured before the driving section.

11. Method according to one of Claims 1 to 9, wherein the method is carried out for two or more driving sections, wherein the final profile depth at the end of the preceding driving section, as estimated for the preceding driving section, is used for the initial profile depth at the beginning of the second or further driving section.

12. Vehicle comprising: i) at least one axle with at least one set of twin tyres having an inner vehicle tyre and an outer vehicle tyre, characterized by ii) one or more driving parameter sensors for determining a plurality of driving parameters (10) of the vehicle during the journey over a predetermined driving distance in a driving section, the plurality of driving parameters (10) comprising at least the lateral acceleration, and iii) an electronic data processing device, the data processing apparatus being configured to carry out the following calculation steps in each case for the inner vehicle tyre and the outer vehicle tyre of the set of twin tyres: cc) calculating, on the basis of the determined driving parameters (10), the forces (12) acting on the vehicle tyre in the driving section and determining an abrasion index (14), assigned to the driving section and determined according to the method disclosed on page 28, line 10 to page 39, line 14 of the original description, from the calculated forces (12) while taking a plurality of influencing parameters (16) into account, the influencing parameters (16) being selected from the group consisting of vehicle parameters (16a), environmental parameters (16b) and tyre parameters (16c), the influencing parameters (16) comprising at least information concerning the tread material of the vehicle tyre and concerning the initial profile depth at the beginning of the driving section, with the position of the respective vehicle tyre in the set of twin tyres being taken into account by a position correction factor (18), and dd) estimating the final profile depth at the end of the driving section for the vehicle tyre on the basis of the respective initial profile depth at the beginning of the driving section while taking the respective abrasion index (14) into account.

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